1. Field of the Invention
The present invention relates to a bending apparatus for bending a knife for working long and thin sheet-like materials (hereinafter merely called "knife"), which is used for die cutting and creasing such sheet-like materials as paper, plastic sheets, corrugated paper, etc to a specified shape by die cut pressing etc.
2. Description of the Prior Art
For example, as shown in FIG. 12, this kind of knife "A" is like a thin band (for example, the thickness is 0.4 mm to 1.0 mm), has a blade edge 1 and is formed so that the section thereof is roughly rectangular. And, during use, the knife "A" is fitted and fixed in a knife insertion groove 3 which has been pierced and consecutively formed on a wooden knife retainer block 2.
The knife insertion groove 3 has been formed in advance to a required shape (shape corresponding to a die cut shape) by, for example, laser beam machining. On the other hand, for the knife "A", the back 6 side thereof is placed along a surface plate, not shown, and at the same time is put and pressed with a set of bending die from both the sides of the knife "A", thereby causing a specified bending portion 5 to be formed.
Hence, in a conventional apparatus used for bending a knife "A" as described above, because the knife "A" springs up or is inclined on the surface plate due to such actions that the knife "A" is put and pressed from both the sides of the knife "A" by a set of die, such a problem as being impossible to obtain an accurate bending angle for the back 6 of the knife "A" occurs.
Furthermore, in the conventional bending apparatus, such a problem as the knife "A" having to be repeatedly put and pressed with the bending die continuously a considerable number of times to conquer a springback phenomenon (resilient rebound) of the knife "A" occurs, thereby preventing any efficient bending process from being carried out.